Catheter having improved rapid exchange junction

ABSTRACT

A balloon catheter, and preferably to a rapid exchange type balloon catheter, having a proximal shaft section, and a distal shaft section with an inner tubular member and an outer tubular member, the outer tubular member having a section which is bonded as by fusing or otherwise bonding. The bonded section extends along a thickened wall portion of the outer tubular member at the rapid exchange junction. A reinforcing member or tube extends within at least a section of the bonded section of the outer tubular member. In one embodiment, the reinforcing tube extends within at least a section of the thickened wall portion of the outer tubular member. The configuration provides a rapid exchange junction with improved kink resistance and flexibility for excellent trackability, and with a minimal decrease in the size of the inflation lumen at the rapid exchange junction for an improved shortened balloon inflation/deflation time.

This application is a continuation of Ser. No. 10/002,477 filed Nov. 1,2001.

BACKGROUND OF THE INVENTION

This invention generally relates to catheters, and particularlyintravascular catheters for use in percutaneous transluminal coronaryangioplasty (PTCA) or for the delivery of stents.

In a typical PTCA procedure, a dilatation balloon catheter is advancedover a guidewire to a desired location within the patient's coronaryanatomy, to position the balloon of the dilatation catheter within thestenosis to be dilated. The balloon is then inflated with radiopaqueliquid at relatively high pressures (generally 4-16 atmospheres) todilate the stenosed region of the diseased artery. One or moreinflations may be needed to effectively dilate the stenosis.Additionally, a stent may be implanted within the artery, typically bydelivery to a desired location within the artery in a contractedcondition on a balloon of a catheter which is similar in many respectsto a balloon angioplasty catheter and expansion to a larger diameter byinflation of the balloon.

In rapid exchange type balloon catheters, the catheter has an inflationlumen extending from the proximal end of the catheter to a balloon on adistal shaft section, a distal guidewire port at the distal end of thecatheter, a proximal guidewire port located distal to the proximal endof the catheter, and a relatively short guidewire lumen extendingtherebetween. The distal shaft section defines the guidewire lumen, anda distal portion of the inflation lumen in fluid communication with theproximal portion of the inflation lumen defined by the single lumenproximal shaft section. The rapid exchange junction located at theproximal guidewire port at the transition between the proximal shaftsection and the distal shaft section should provide a good transition inflexibility from the relatively stiff proximal shaft section to therelatively flexible distal shaft section to facilitate tracking thecatheter within the patient's tortuous vasculature. One difficulty hasbeen forming a rapid exchange junction with the desired characteristicsof flexibility, kink resistance, and pushability (i.e., the ability totransmit force from the proximal end to the distal end of the catheter).

To help meet the desire for a catheter having sufficient pushability andcrossability, while maintaining trackability, prior art designs havesupplemented polymer catheter shafts with a support mandrel. Other priorart designs have addressed these handling and performance issues byusing materials of different stiffness for the proximal and distalportions of the catheter, and employing a high strength metallicproximal shaft section, commonly called a hypotube. To prevent kinkingat the junction of these two materials, while maintaining trackabilityand pushability, some conventional designs have employed reinforcinglayers or stiffening wires to bridge the transition in catheter shaftmaterial. Despite these attempts, prior art designs have suffered fromvarious drawbacks relating to these handling and performance issues.

Accordingly, it would be a significant advance to provide a catheterhaving an improved rapid exchange junction.

SUMMARY OF THE INVENTION

The invention is directed to a balloon catheter, and preferably to arapid exchange type balloon catheter, having a proximal shaft section,and a distal shaft section with an inner tubular member and an outertubular member, the outer tubular member having a section which isbonded as by fusing or otherwise bonding (i.e., “the bonded section”) tothe inner tubular member. The bonded section extends along a thickenedwall portion of the outer tubular member at the rapid exchange junction.A reinforcing member or tube extends within at least a section of thebonded section of the outer tubular member. In one embodiment, thereinforcing tube extends within at least a section of the thickened wallportion of the outer tubular member. The configuration provides a rapidexchange junction with improved kink resistance and flexibility forexcellent trackability, and with a minimal decrease in the size of theinflation lumen at the rapid exchange junction for an improved shortenedballoon inflation/deflation time.

The balloon catheter of the invention generally comprises an elongatedshaft having the proximal shaft section and distal shaft section, aninflation lumen, a guidewire receiving lumen extending in the distalshaft section, and a balloon on the distal shaft section with aninterior in fluid communication with the inflation lumen. The proximalshaft section defines a proximal portion of the inflation lumen, and ispreferably a metallic tubular member such as a hypotube, although highstrength polymers such as polyetheretherketone (PEEK), and polyamide mayalternatively be used. The outer tubular member of the distal shaftsection defines a distal portion of the inflation lumen in fluidcommunication with the proximal shaft section and the balloon. The innertubular member within the distal portion of the inflation lumen definesthe guidewire lumen in fluid communication with a guidewire distal portat the inner tubular member distal end and a guidewire proximal port atthe inner tubular member proximal end.

As a rapid exchange type catheter, the proximal guidewire port islocated in the distal shaft section, distal to the proximal end of thecatheter shaft, and preferably a relatively short distance from theballoon and a relatively long distance from the proximal end of thecatheter. The proximal guidewire port at the rapid exchange junction isformed by placing the inner tubular member through a hole cut in theouter tubular member side wall, and then bonding part of thecircumference of the inner tubular member to the outer tubular member toform the bonded section. The bonded section forms the transition betweenthe single lumen proximal portion of the shaft, and the distal portionof the shaft having the guidewire lumen and the distal portion of theinflation lumen.

In a presently preferred embodiment, the bonded section is formed bythermally bonding (i.e., fusing) the inner tubular member to the outertubular member by applying heat to melt the polymeric material and fusethe members together. However, the bonded section can be formed byadhesively bonding or a combination of adhesively bonding and thermallybonding the inner and outer members together. Although discussed belowprimarily in terms of the preferred, fusion bonded embodiment in whichthe bonded section consists of a fused section, it should be understoodthat the discussion below also applies to the embodiments in which thebonded section is formed in whole or in part by methods other thanfusion bonding. In a presently preferred embodiment, the fused sectionhas a relatively short length, which, in one embodiment, extends fromthe proximal end of the inner tubular member to a location proximal tothe distal end of the outer tubular member. The fused section ispreferably formed by locally applying the heat in a focused manner tojust the portion of the shaft extending from the guidewire proximal portdistally about 1 cm or less. In a presently preferred embodiment, thefused section has a length of about 0.1 to about 1 cm. As a result, thetransition formed by the fused section at the rapid exchange junctionprovides a minimal decrease in the overall size of the inflation lumenas a result of the junction, to thereby minimize the ballooninflation/deflation times.

The thickened wall portion of the outer tubular member is fused to theinner tubular member to form at least a portion of the fused section ofthe outer tubular member. The thickened wall portion has an innerperiphery with a first segment which is bonded to part of an outersurface of the inner tubular member and which extends around part of theinner periphery of the thickened wall portion, and a second segmentwhich is not bonded to the inner tubular member and which extends aroundthe remaining part of the inner periphery of the thickened wall portionof the outer tubular member. In one embodiment, about 10% to about 95%,preferably about 10% to about 70%, and more specifically about 10% toabout 50% of an outer periphery (extending around part of thecircumference) of the inner tubular member is bonded to the thickenedwall portion of the outer tubular member to form the first segment ofthe inner periphery of the thickened wall portion (i.e., it extendsaround about 36 to about 320 degrees, preferably about 36 to about 250degrees of a 360° outer periphery of the inner tubular member).

The reinforcing tube within the fused section extends within the outertubular member of the distal shaft section without necessarily beingbonded, e.g., fused or adhesively bonded, thereto. For example, thereinforcing tube can be friction fit within the outer tubular member.Alternatively, part or all of the length of the reinforcing tube can bebonded to the outer tubular member. In one embodiment, at least thedistal end of the reinforcing tube is not bonded to the distal outertubular member, for increased flexibility at the rapid exchangejunction. The reinforcing tube is preferably formed of a polymericmaterial selected from the group consisting of PEEK, polyimide, andother high modulus engineering thermoplastic/thermoset polymers such aspolytetrafluoroethylene (PTFE), e.g., TEFLON. The inflation lumenextending within the thickened wall portion of the outer tubular membermay be defined by the reinforcing tube extending therein, in which casethe second segment of the inner periphery of the outer tubular memberthickened wall portion is in contact with the reinforcing tube. In analternative embodiment, the inflation lumen extending within thethickened wall portion of the outer tubular member is defined by thethickened wall portion itself, in which case the distal end of thereinforcing tube is located proximal to the distal end of the thickenedwall portion of the outer tubular member.

The thus formed distal shaft section provides a distal subassembly whichcan be attached to any type of proximal shaft section, typically byadhesive or fusion bonding the proximal end of the outer tubular memberto the distal end of a desired proximal shaft section. In oneembodiment, the proximal end of the outer tubular member and thereinforcing tube therein are bonded to the distal end of the proximalshaft section.

The catheter of the invention has excellent ability to track within thepatient's tortuous vasculature due to the improved rapid exchangejunction. The fused section of the outer tubular member, with at least asection of the reinforcing tube extending therein and formed at least inpart by the thickened wall portion of the outer tubular member, providesa rapid exchange junction with high pushability and flexibility.Moreover, the rapid exchange junction has a short length, whichconsequently provides for an improved, minimized inflation/deflationduration. These and other advantages of the invention will become moreapparent from the following detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view, partially in section, of a rapid exchangeballoon catheter which embodies features of the invention.

FIG. 2 is a transverse cross sectional view of the catheter shown inFIG. 1, taken along line 2—2.

FIG. 3 is a transverse cross sectional view of the catheter shown inFIG. 1, taken along line 3—3.

FIG. 4 is a transverse cross sectional view of the catheter shown inFIG. 1, taken along line 4—4.

FIG. 5 is a transverse cross sectional view of the catheter shown inFIG. 1, taken along line 5—5.

FIG. 6 is a transverse cross sectional view of the catheter shown inFIG. 1, taken along line 6—6.

FIG. 7 is a longitudinal cross sectional view of an of an alternativerapid exchange junction which embodies features of the invention, havinga reinforcing tube extending within a thickened wall section of theouter tubular member.

FIG. 8 is a transverse cross sectional view of the catheter shown inFIG. 7, taken along line 8—8.

FIG. 9 is a longitudinal cross sectional view of an of an alternativerapid exchange junction which embodies features of the invention, havingthe distal end of the proximal shaft section hypotube distal to theproximal guidewire port.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates rapid exchange type stent delivery balloon catheter10 embodying features of the invention. Catheter 10 generally comprisesan elongated catheter shaft 11 having a proximal end 12, a distal end13, and an inflatable balloon 14 on a distal shaft section. Anexpandable tubular stent 16 is mounted on balloon 14 for implanting inthe patient's body lumen. The shaft 11 has a proximal shaft section 18,a distal shaft section 19 at the distal end of the proximal shaftsection, an inflation lumen 20, and a guidewire receiving lumen 21. Theproximal shaft section 18 comprises a high strength tubular member 22which is preferably a metallic tubular member such as a stainless steelor NiTi tubular member. In the embodiment illustrated in FIG. 1, apolymeric outer layer 23 is provided on the outer surface of themetallic tubular member 22. Polymeric outer layer 23 is preferablyformed of a coextrusion of polyether block amide (PEBAX) and adhesivepolymer such as Primacor, although a variety of suitable polymericmaterials can be used including nylon and polyurethane. The metallictubular member 22 defines a proximal portion of the inflation lumen 20.The distal end of the metallic tubular member 22 tapers distally to asmaller transverse dimension, as is conventional in the design ofproximal catheter shafts formed of a hypotube. FIGS. 2-4 illustratetransverse cross sections of the catheter of FIG. 1, taken along thelength of the metallic tubular member 22 along lines 2—2, 3—3, and 4—4,respectively. In the embodiment illustrated in FIG. 4, the taperedportion of the metallic tubular member 22 has a C-shaped cross sectionextending only partially around the circumference of the shaft. Thedistal shaft section 19 comprises an outer tubular member 26 defining adistal portion of the inflation lumen 20, and an inner tubular member 27defining the guidewire lumen 21 in fluid communication with a guidewiredistal port 28 at the distal end of the inner tubular member 27 and aguidewire proximal port 29 at the proximal end of the inner tubularmember 27. In the embodiment of FIG. 1, the distal shaft section 19 andthe proximal shaft section 18 overlap at their proximal and distal ends,respectively, to form a lap joint. A rapid exchange junction at theguidewire proximal port 29 is the transition between the single lumenproximal shaft section and the multilumen distal shaft section. Anadapter 30 at the proximal end of the catheter provides access to theinflation lumen 20. Balloon 14 has a proximal end sealingly secured tothe distal end of outer tubular member 26 and a distal end sealinglysecured to the distal end of inner tubular member 27, so that itsinterior is in fluid communication with inflation lumen 20. The distalend of catheter may be advanced to a desired region of a patient's bodylumen in a conventional manner and balloon 14 inflated to expand stent16. The catheter 10 is withdrawn after deflating the balloon 14, leavingthe implanted stent 16 in the body lumen.

A bonded section 31 of the outer tubular member is bonded to the innertubular member, preferably by fusion bonding (hereafter “the fusedsection 31”). The fused section 31 extends from the proximal end of theinner tubular member 27 to a location proximal to the distal end of theouter tubular member 26, which in the embodiment of FIG. 1 is spacedproximally from the proximal end of the balloon 14. In a presentlypreferred embodiment, the fused section 31 has a length of about 1 toabout 10 mm, and more specifically about 5 to about 7 mm, and is about0.3 to about 0.6% of the total length of the catheter shaft. In theembodiment of FIG. 1, the section of the inner tubular member 27 distalto the fused section 31 is disposed in the outer tubular member lumenwithout being fused thereto, which provides a flexible distal shaftsection with a minimal decrease in the inflation lumen area. Theproximal section of the inner tubular member 27 is eccentricallydisposed in the outer tubular member lumen, as best illustrated in FIG.5, showing a transverse cross section of the catheter 10 of FIG. 1,taken along line 5—5. The distal section of the inner tubular member 27is coaxially disposed in the outer tubular member lumen, as bestillustrated in FIG. 6, showing a transverse cross section of thecatheter of FIG. 1, taken along line 6—6.

The outer tubular member 26 has a thickened wall portion 32 in the fusedsection 31. In the embodiment of FIG. 1, the thickened wall portion 32of the outer tubular member 26 is located distal to the guidewireproximal port 29, although in an alternative embodiment (not shown) itmay have a proximal end located proximal to the guidewire proximal port29. In a presently preferred embodiment, the thickened wall portion 32has a length of about 1 to about 10 mm, and more specifically about 5 toabout 7 mm. The thickened wall portion 32 has an inner periphery with afirst segment 33 which is fused to part of an outer surface of the innertubular member 27, and a second segment 34 which is not fused to theinner tubular member. The first segment 33 extends around part of theinner periphery of the thickened wall portion 32, and the second segment34 extends around the remaining part of the periphery of the innerperiphery of the thickened wall portion 32 radially adjacent to thefirst segment. In the embodiment illustrated in FIG. 5, about 70% of theouter surface of the inner tubular member 27 is bonded to the thickenedwall portion 32, to form the first segment 33 of the inner periphery ofthe outer tubular member 26 thickened wall portion 32.

A reinforcing tube 36 extends within at least a section of the fusedsection 31 of the outer tubular member 26 (i.e., the reinforcing tube 36distal end is distal to the proximal end of the fused section 31). Thereinforcing tube 36 is preferably formed of a relatively high strengthpolymeric material which provides the rapid exchange junction at theguidewire proximal port 29 with more flexibility than the metallictubular member 22 of the proximal shaft section 18. In a presentlypreferred embodiment, the reinforcing tube 36 is formed of PEEK. In theembodiment illustrated in FIG. 1, the distal end of the reinforcing tube36 is located at the proximal end of the thickened wall portion 32 ofthe outer tubular member 26, at the guidewire proximal port 29, althoughin alternative embodiments, it may be located distal thereto. With thedistal end of the reinforcing tube 36 proximal to the distal end of thethickened wall portion of the outer tubular member 26, the inflationlumen 20 extending within the thickened wall portion 32 of the outertubular member 26 is defined by the thickened wall portion 32.

The distal shaft section 19 comprises a subassembly which can be joinedto a variety of proximal shaft sections by bonding the proximal end ofthe outer tubular member 26 to the proximal shaft section. Thesubassembly is formed by positioning the distal end of the inner tubularmember 27 in a hole or port in the side wall of the outer tubular member26. A mandrel (not shown), which has a distal end tapering to a smallerdiameter along side the inner tubular member 27, is positioned in theinflation lumen, to keep the inflation lumen open during the fusing ofthe inner and outer tubular members. The subassembly is completed byapplying heat to fuse the inner and the outer tubular members 27/26together and form the fused section 31. During the fusing, the polymericmaterial forming the outer tubular member 26 flows and fills in aroundthe tapered mandrel to thereby form the thickened wall portion 32 of theouter tubular member 26. In the embodiment illustrated in FIG. 5, thefused section 31 has an oval or elliptical transverse cross section as aresult of the fusing process. The inflation lumen 20 thus tapers to asmaller diameter in the fused section 31 of the outer tubular member 26,however, because the length of the fused section 31 is minimized, theeffect on the inflation/deflation time of the catheter 10 is minimized.The tapered mandrel is then removed and the distal shaft section 19secured to the proximal shaft section 18 to complete the shaft assembly.In the embodiment of FIG. 1, the distal end of the metallic tubularmember 22 is positioned within the reinforcing tube 36, and the proximalend of the reinforcing tube 36 is bonded by gluing with an adhesive tothe distal end of the metallic tubular member 22. The distal end of thereinforcing tube 36 is positioned within the outer tubular member 26,into contact therewith and, in a presently preferred embodiment, notbonded thereto. The proximal end of the outer tubular member 26 is thenbonded to the distal end of the proximal shaft section 18, as in theembodiment of FIG. 1, by fusion or adhesively bonding to the polymericouter layer 23 of the metallic tubular member 22.

In a presently preferred embodiment, the outer tubular member 26comprises a first section 40 formed of a first polymeric material, and asecond section 41 bonded to the distal end of the first section 40 andformed of a second polymeric material different from the first polymericmaterial. The second polymeric material preferably is fusion bondable tothe polymeric material of the balloon 14, and may have a lower ShoreDurometer hardness than the first polymeric material. The firstpolymeric material is preferably a polyamide such as nylon 12, however avariety of suitable materials may be used including polyether blockamide (PEBAX) and polyurethane. The second polymeric material ispreferably a polyamide copolymer such as PEBAX, and specifically PEBAX72D, available from Autochem, however a variety of suitable materialsmay be used including polyurethane and nylon. In the embodiment of FIG.1, the distal end of the thickened wall portion 32 of the outer tubularmember is located proximal to the second section 41 of the outer tubularmember, so that the first section 40 of the outer tubular membercomprises the thickened wall portion 32 and portions on either end ofthe thickened wall portion having a smaller wall thickness than thethickened wall section. Similarly, the distal end of the fused section31 of the outer tubular member is located proximal to the second section41 of the outer tubular member.

FIG. 7 illustrates an alternative embodiment, in which the reinforcingtube 36 extends within at least a section of the thickened wall portion32 of the outer tubular member 26 to a location along the length of thethickened wall portion 32 or alternatively to a location distal to thethickened wall portion 32. In the embodiment of FIG. 7, the distal endof the reinforcing tube 36 is at the distal end of the thickened wallportion 32. The reinforcing tube 36 distal end is typically necked orotherwise reduced in diameter to extend within the smaller innerdiameter of the thickened wall portion 32. Preferably, the reduceddiameter distal section of the reinforcing tube 36 is not fused orotherwise bonded to the outer tubular member 26, for added flexibility.In the embodiment of FIG. 7, about 90% to about 95% of the outer surfaceof the inner tubular member 27 is bonded to the inner periphery of thethickened wall portion 32 of the outer tubular member 26, to form thefirst segment 33 of the inner periphery of the outer tubular member 26thickened wall portion 32, as best illustrated in FIG. 8 showing atransverse cross section of the catheter of FIG. 7, taken along line8—8. As with the embodiment of FIG. 1, the second segment 34 of theouter tubular member 26 is not bonded to the inner tubular member 27,although it may be at least in part bonded to the reinforcing tube 36extending therein. With the distal end of the reinforcing tube 36located at the distal end of the thickened wall portion 32 of the outertubular member 26, the inflation lumen 20 extending within the thickenedwall portion 32 is defined by the reinforcing tube 36 extending therein,and the second segment 34 of the inner periphery of the thickened wallportion 32 of the outer tubular member 26 is in contact with thereinforcing tube 36.

FIG. 9 illustrates an alternative embodiment of the invention, in whichthe metallic tubular member 22 has a distal end located distal to theproximal guidewire port 29. In the embodiment illustrated in FIG. 9, thereinforcing tube 36 extends to a location distal to the thickened wallportion 32. The distal end of the reinforcing tube 36 is preferablyproximal to the second section 41 of the outer tubular member 26, andspecifically, the distal end of the reinforcing tube 36 is preferablyabout 5 mm or less from the distal end of the thickened wall portion 32.

The catheter shaft will generally have the dimensions of conventionaldilatation or stent delivery catheters. The length of the catheter 10,measured from the distal end of the adapter 30 to the distal end of thecatheter is about 90 to about 150 cm, typically about 143 cm. Themetallic tubular member 22 of the proximal shaft section 18 has a lengthof about 110 to about 115 cm, typically about 114 cm, an outer diameter(OD) of about 0.025 to about 0.02 inches, and an inner diameter (ID) ofabout 0.015 to about 0.0185 inches. The outer tubular member 26 of thedistal shaft section 19 has a length of about 15 to about 25 cm,typically about 23 cm, an OD of about 0.029 to about 0.036 inches, andan ID of about 0.025 to about 0.030 inches. The inner tubular member 27of the distal shaft section 19 has a length of about 25 to about 30 cm,typically about 28 cm, an OD of about 0.018 to about 0.025 inches, andan ID of about 0.014 to about 0.018 inches. The inner and outer tubularmembers 27/26 may taper in the distal section to a smaller OD or ID.

The balloon 14 may be formed of a variety of suitable compliant, semi-or non-compliant, or hybrid compliant materials depending on the use ofthe catheter, e.g., dilatation, stent delivery, etc. The length of theballoon 14 is typically about 10 to 50 mm, more specifically about 20 to30 mm. In an expanded state, the balloon diameter is typically about 0.5to about 4.5 mm, more specifically about 1.5 to about 4 mm. The wallthickness will vary depending on the burst pressure requirements andhoop strength of the balloon material.

While the present invention is described herein in terms of certainpreferred embodiments, those skilled in the art will recognize thatvarious modifications and improvements may be made to the inventionwithout departing from the scope thereof. Moreover, although individualfeatures of one embodiment of the invention may be discussed herein orshown in the drawings of the one embodiment and not in otherembodiments, it should be apparent that individual features of oneembodiment may be combined with one or more features of anotherembodiment or features from a plurality of embodiments.

1. A balloon catheter, comprising: a) an elongated shaft having aninflation lumen and a guidewire lumen, and i) a proximal shaft sectioncomprising a tubular member, defining a proximal portion of theinflation lumen; ii) a distal shaft section at the distal end of theproximal shaft section, having an outer tubular member defining a distalportion of the inflation lumen, and an inner tubular member defining theguidewire lumen in fluid communication with a guidewire distal port atthe distal end of the inner tubular member and a guidewire proximal portat the proximal end of the inner tubular member, the outer tubularmember having a bonded section along which the inner tubular member isbonded thereto and which extends from the proximal end of the innertubular member to a location proximal to the distal end of the outertubular member, and the outer tubular member having a thickened wallportion in the bonded section thereof, the thickened wall portion havingan inner periphery with a first segment which is bonded to part of anouter surface of the inner tubular member and which extends around partof the inner periphery of the thickened wall portion, and a secondsegment which is not bonded to said inner tubular member and whichextends around a remaining part of the inner periphery of the thickenedwall portion; and iii) a reinforcing tube extending within at least asection of the bonded section of the outer tubular member; and b) aninflatable balloon on the distal shaft section having a proximal endsecured to the outer tubular member, a distal end secured to the innertubular member, and an interior in fluid communication with theinflation lumen.
 2. The balloon catheter of claim 1 wherein the bondedsection of the outer tubular member has a distal end spaced proximallyapart from the balloon.
 3. The balloon catheter of claim 1 wherein thebonded section of the outer tubular member has a length of about 1 toabout 10 mm.
 4. The balloon catheter of claim 1 wherein the thickenedwall portion of the outer tubular member is distal to the guidewireproximal port.
 5. The balloon catheter of claim 1 wherein the thickenedwall portion of the outer tubular member has a length of about 1 toabout 10 mm.
 6. The balloon catheter of claim 1 wherein the reinforcingtube has a distal end located proximal to the thickened wall portion ofthe outer tubular member.
 7. The balloon catheter of claim 1 wherein thereinforcing tube has a distal end located distal to the proximal end ofthe thickened wall portion of the outer tubular member.
 8. The ballooncatheter of claim 1 wherein the reinforcing tube has a proximal sectionbonded to the proximal shaft section.
 9. The balloon catheter of claim 1wherein the reinforcing tube has a proximal section bonded to an outersurface of the metallic tubular member of the proximal shaft section.10. The balloon catheter of claim 9 wherein the tubular member of theproximal shaft section is a metallic tubular member having an outerpolymeric layer, the outer polymeric layer having a distal end abuttinga proximal end of the reinforcing tube.
 11. The balloon catheter ofclaim 10 wherein the outer tubular member has a proximal section bondedto the outer polymeric layer of the proximal shaft section metallictubular member.
 12. The balloon catheter of claim 1 having a sideopening extending through a sidewall of the outer tubular member, with asection of the inner tubular member in the side opening and fused to thesidewall of the outer tubular member to form the guidewire proximalport.
 13. The balloon catheter of claim 12 wherein about 10% to about95% of an outer periphery of the inner tubular member is bonded to theinner periphery of the outer tubular member thickened wall portion toform the first segment of the inner periphery of the thickened wallportion.
 14. The balloon catheter of claim 1 wherein the second segmentof the inner periphery of the outer tubular member thickened wallportion is in contact with an outer surface of the reinforcing tube. 15.The balloon catheter of claim 1 wherein the outer tubular membercomprises a first section formed of a first polymeric material, and asecond section distal to and bonded to the first section and formed of asecond polymeric material different from the first polymeric material.16. The balloon catheter of claim 15 wherein the first section of theouter tubular member comprises the thickened wall portion and portionson either end of the thickened wall portion having a smaller wallthickness than the thickened wall portion.
 17. The balloon catheter ofclaim 15 wherein the thickened wall portion of the outer tubular memberhas a distal end proximal to the second section of the outer tubularmember.
 18. The balloon catheter of claim 15 wherein the bonded sectionof the outer tubular member has a distal end proximal to the secondsection of the outer tubular member.
 19. The balloon catheter of claim15 wherein the first section of the outer tubular member is formed ofnylon and the second section of the outer tubular member is formed ofpolyether block amide.
 20. The balloon catheter of claim 1 wherein thereinforcing tube is formed of a polymeric material selected from thegroup consisting of polyetheretherketone, polyimide, andpolytetrafluoroethylene.
 21. A rapid exchange type balloon catheter,comprising: a) an elongated shaft having an inflation lumen and aguidewire lumen, and i) a proximal shaft section comprising a metallictubular member, defining a proximal portion of the inflation lumen; ii)a distal shaft section at the distal end of the proximal shaft section,having an outer tubular member defining a distal portion of theinflation lumen, and an inner tubular member defining the guidewirelumen in fluid communication with a guidewire distal port at the distalend of the inner tubular member and a guidewire proximal port at theproximal end of the inner tubular member, the outer tubular memberhaving a fused section along which the inner tubular member is fusedthereto and which extends from the proximal end of the inner tubularmember to a location proximal to the distal end of the outer tubularmember, and the outer tubular member having a thickened wall portion inthe fused section thereof, the thickened wall portion having an innerperiphery with a first segment which is fused to part of an outersurface of the inner tubular member and which extends around part of theinner periphery of the thickened wall portion, and a second segmentwhich is not bonded to said inner tubular member and which extendsaround a remaining part of the inner periphery of the thickened wallportion; and iii) a reinforcing tube extending within at least a sectionof the outer tubular member thickened wall portion; and b) an inflatableballoon on the distal section having a proximal end secured to the outertubular member, a distal end secured to the inner tubular member, and aninterior in fluid communication with the inflation lumen.
 22. Theballoon catheter of claim 21 wherein the thickened wall portion of theouter tubular member is distal to the guidewire proximal port.
 23. Theballoon catheter of claim 21 wherein the thickened wall portion of theouter tubular member has a length of about 1 to about 10 mm.
 24. Theballoon catheter of claim 21 wherein the reinforcing tube has a proximalsection bonded to the proximal shaft section.
 25. The balloon catheterof claim 21 wherein the reinforcing tube has a proximal section bondedto an outer surface of the metallic tubular member of the proximal shaftsection.
 26. The balloon catheter of claim 25 wherein the metallictubular member of the proximal shaft section has an outer polymericlayer with a distal end abutting a proximal end of the reinforcing tube.27. The balloon catheter of claim 26 wherein the outer tubular memberhas a proximal section bonded to the outer polymeric layer of theproximal shaft section metallic tubular member.
 28. The balloon catheterof claim 21 having a side opening extending through a sidewall of theouter tubular member, with a section of the inner tubular member in theside opening and fused to the sidewall of the outer tubular member toform the guidewire proximal port.
 29. The balloon catheter of claim 21wherein about 10% to about 95% of an outer surface of the inner tubularmember is bonded to the inner periphery of the outer tubular memberthickened wall portion to form the first segment of the inner peripheryof the thickened wall portion.
 30. The balloon catheter of claim 21wherein the outer tubular member comprises a first section formed of afirst polymeric material, and a second section distal to and bonded tothe first section and formed of a second polymeric material differentfrom the first polymeric material.
 31. The balloon catheter of claim 30wherein the first section of the outer tubular member comprises thethickened wall portion and portions on either end of the thickened wallportion having a smaller wall thickness than the thickened wall portion.